The objective is development and commercialization of a new method for direct labeling of antibodies with Technetium-99m. In this method, called the regulated reduction method, one chemical means is used to break the disulfide bonds in the protein, the reduced protein is then purified, and a separate chemical means used to reduce the sodium pertechnetate. Stabilizers and transfer ligands are added to the product. Frozen and lyophilized product will be produced, which can be labeled in a single step by the addition of Sodium Pertechnetate and a single fifteen minute incubation. No post labeling purification is required. Using this method, there is no detectable transchelation and radiochemical purity over 93% can be obtained. The method will be formated in a simple kit, containing lyophilized product. The regulated reduction method will be applied to three anti-TAG-72 monoclonal antibodies, using anti-CEA and human polyclonal IgG as a control. Animal blood clearance and biodistribution studies will be conducted, preparatory to human clinical trials. A new and simple Tc- 99m labeling method has wide application for diagnostic imaging with monoclonal antibodies.